When vessels filled with suspensions containing solids are emptied, solid deposits form on the bottom of the vessel to an increased extent, particularly with low filling levels. This is attributed to the fact that the agitating devices arranged in such vessels lose effectiveness as the filling level drops. However, it is necessary to discharge the deposits towards the outlet opening in order to reliably avoid accumulation of solids at the bottom of the vessel. This is especially the situation with vessels receiving radioactive liquids.
In nuclear reprocessing facilities, upright and lying circular vessels as well as annular vessels (so-called annular-slab vessels) are installed with the base walls thereof being at a slight inclination towards the discharge line. In this context, it has been proposed to mount spraying arrangements in the vicinity of the base wall or in the vicinity of the inner walls by means of which the solid deposits can be flushed out. In this connection, it is unsatisfactory that large amounts of flushing liquid are required for large vessels. These large amounts of flushing liquid required after emptying a vessel lead, with radioactive product solutions, to an undesirable increase of secondary waste, the removal of which is very costly. Another disadvantage is that the valuable substances of the radioactive product solution are present in a very highly diluted form because of the flushing liquid and this affects the economical processing of the product solution. Substantially increasing the inclination of the base of the vessel cannot be regarded as a satisfactory solution for reducing the amount of flushing liquid, since otherwise the height of the vessel would have to be considerably increased, especially with respect to annular vessels. This would require additional space which can be made available only at very high cost in a nuclear facility.